Microporous materials are of commercial interest in catalysis, adsorption and ion-exchange. Due to active site confinement, high surface areas and robust hydrothermal stability, these materials often display enhanced and advantageous properties. Lately, there has been increasing interest in materials that incorporate 8 membered T-atom rings (8MRs) in their structure for catalytic applications. Both silicoaluminophosphate (SAPO) and aluminosilicate (zeolite) compositions are of interest in this context. The two most prominent catalytic applications of 8MR molecular sieves are the methanol-to-olefins reaction (MTO) and the selective catalytic reduction (SCR) of NOx in flue and exhaust gases. SAPO-34, a material that has the CHA topology, is commercially applied in MTO, while its aluminosilicate analogue, Zeolites are more attractive catalysts in general, compared to SAPOs, because of a variety of properties including their higher (hydro)thermal stability and stronger acidity. This preference is reflected in their dominant presence in refining processes and petrochemistry. Given the similar topological needs for both MTO and deNOx, it could be beneficial if one zeolite could be made into an efficient catalyst for both applications. So far, few zeolite compositions that are highly active for MTO are efficient for deNOx or vice versa, the problem being the difference in optimal Si/Al ratios for both applications. DeNOx ideally operates on zeolites with low Si/Al molar ratios (<20), in order to achieve high active site (ion-exchanged Cu) loadings, whereas MTO is usually run with Si/Al ratios of over 20, owing to the increased deactivation and poor selectivities on zeolites with high Al content.
Promising 8MR materials include LEV, AFX, KFI, RTH and AEI framework topologies. The cage size and pore dimensionality are critical to the catalytic performance and stability of these materials. The AEI molecular sieve topology, in particular, describes a microporous material where the 8MRs constitute a 3D channel system (8×8×8) with equal pore sizes of 3.8×3.8 Å and medium size cages that can include spheres up to 7.3 Å. AEI molecular sieves display unique activity and selectivity patterns in MTO (e.g., H-SAPO-18 or zeolite H-SSZ-39) and, when exchanged with Cu2+, in SCR. Moreover, the stability of the SSZ-39 zeolite is found high compared to the industrial standard 8MR zeolite (SSZ-13). Collectively, these reports suggest that SSZ-39 is a likely candidate for large-scale applications provided that the material can be synthesized efficiently. The latter is a common bottleneck hindering the exploitation of many unique zeolite topologies.
The present invention is directed to allowing an expanded range of OSDAs for use in preparing some of these materials as well as solving some of these shortcomings.